Cable sealant composition and method of sealing cable

ABSTRACT

A cable sealant to seal the voids between the strands of electrical and similar cables to prevent water flow through same and to seal the cable elements from the atmosphere. The preferred cable sealant composition comprises about 10 percent by weight ethylene propylene rubber copolymer, about 40 percent discrete particles of butadiene-acrylonitrile rubber copolymer, about 15 percent polypropylene, about 11 percent polyethylene, about 10 percent paraffin wax and about 13 percent liquid parafinnic hydrocarbons. About 1 percent of colorant such as iron oxide is normally added to this composition, which is blended to form the cable sealant. A method of sealing cable by filling the voids between cable strands with the above composition at a temperature preferably in the range between 225* and 275*F.

United States Patent 11 1 Strecker et al.

CABLE SEALANT COMPOSITION AND METHOD OF SEALING CABLE Inventors: Larry A. Strecker; James E. Wood,

both of St. Louis, Mo.

Assignee: Inmont Corporation, New York,

Filed: Sept. 4, 1973 Appl. No.: 393,761

Related US. Application Data Division of Ser. No. 227,956, Feb. 22, 1972.

US. Cl 174/23 C, 156/48, 174/179, 117/232, 161/144, 161/175, 260/5, 260/889, 260/28.5 A, 260/28.5 AV, 260/28.5 B

Int. CL... HOlb 3/30, HOlb 7/02 Field of Search 2.60/285 A, 28.5 B, 889, 260/3l.8 M, 31.8 DR; 252/182; 174/23 R, 23

, p I References Cited UNITED STATES PATENTS 11/1965 Flanagan 260/28.5 A 11/1967 Wheat 260/28.5 B

11/1968 Boyer ..260/889 9/1970 Minekawa ..260/889 1451 Sept. 17, 1974 3,536,652 10/1970 Bickel et a1 260/28.5 A 3,645,817 2/1972 Walker 156/275 3,672,974 6/1972 Tomlinson 156/48 Primary Examiner-George F. Lesmes Assistant Examiner-R. J. Roche Attorney, Agent, or Firm-Philip R. Arvidson [57] ABSTRACT A cable sealant to seal the voids between the strands of electrical and similar cables to prevent water flow through same and to seal the cable elements from the atmosphere. The preferred cable sealant composition comprises about 10 percent by weight ethylene propylene rubber copolymer, about 40 percent discrete particles of butadiene-acrylonitrile rubber copolymer,

about 15 percent polypropylene, about 11 percent polyethylene, about 10 percent paraffin wax and about 13 percent liquid parafinnic hydrocarbons. About 1 percent of colorant such as iron oxide is normally added to this composition, which is blended to form the cable sealant.

A method of sealing cable by filling the voids between cable strands with the above composition at a temperature preferably in the range between 225 and 275F.

4 Claims, 2 Drawing Figures CABLE SEALANT COMPOSITION AND METHOD OF SEALING CABLE This is a division, of application Ser. No. 227,956 filed 2/22/72.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to sealant compositions for cable such as electrical cable. Among other uses, such sealants are employed in cable used in ships in order to prevent water flow between supposedly water tight compartments through the voids in electrical and similar cable. Such cable sealants also provide increased cable life due to isolation of the cable strands from the atmosphere.

2. Description of the Prior Art Cable sealants are, of course, known in the art. However; such sealants have normally employed semidrying polyesters or vegetable oil derived materials filled with inert fillers. Such cable sealants harden after a few years to such an extent that the sealant will fracture if the cable is flexed, causing in turn seal failure and probable malfunction.

Other known cable sealants have used polybutene polymers to avoid the above problems. However, the polybutene polymers have been found to attack common cable components such as polyethylene.

Another disadvantage of existing cable sealants is that they tend to adhere to deck and other areas when pieces of the sealant are removed from cable and discarded durng splicing operations. Due to the danger of tire and toxic gases in the confined spaces aboard ship, removal of these splicing scraps from deck areas has required use of non-toxic and non-flammable solvents such as Freons. Such solvents are, of course, quite expensive.

SUMMARY OF THE INVENTION Applicants have now developed a novel cable sealant composition which preferably comprises a blend of ethylene propylene rubber copolymer, discrete particles of butadiene acrylonitrile copolymer, polypropylene, polyethylene, paraffmic hydrocarbons and colorant.

This invention involves a unique composition that has many of the properties of a high molecular weight rubber elastomer such as resilience, low temperature flexibility, temperature resistance and inertness. Examples of high molecular weight elastomers are cured silicone, Neoprene and butyl rubbers. These rubbers themselves cannot be used because they do not lend themselves to deposit by pumping. By contrast, the compositions of this invention can be deposited by pumping. Also, because the butadiene-acrylonitrile copolymer is dispersed as discrete particles in the somewhat wax-like relatively low molecular weight hydrocarbon blend comprising the rest of the sealant, the

sealant has very low cohesive strength which allows for easy removal from a cable. The butadiene-acrylonitrile copolymer is a relatively polar polymer which is sufficiently incompatible or non-miscible so that it stays as discrete particles in the continuous wax-like phase comprising the remainder of the sealant.

Also, this composition has been found to retain its elastomeric properties over a long period of time, thus extending cable life to periods such as twelve years, almost triple that of currently employed cables.

Furthermore, the cable sealant of this invention clings to the interior portions of cable cover and to the exterior of the strands of the cable but has been found not to adversely affect the cable components. For example, it does not craze, crack, solvate or swell such common cable components as polyethylene, vinyl materials such as polyvinyl chloride, impregnated fabrics, silicones, and Nylon or Mylar films. Finally, when stripped from the cable during splicing operations, the cable sealant of this invention strips easily and quickly. Also when pieces of cable sealant are discarded on deck and other surfaces, they do not adhere to such surfaces and are readily swept up, since this sealant composition has no adhesion to other materials unless applied to them while heated.

BRIEF DESCRIPTION OF THE DRAWING Referring more particularly to FIG. 2, this figure differs from FIG. 1 in that the void areas 3 have been filled with the cable sealant composition 3' of this invention, thus effectively sealing the interior of the cable, rendering it water tight and also protecting the cable strands from the effects of atmospheric penetration.

DESCRIPTION OF THE PREFERRED EMBODIMENT A typical formulation for the sealant composition of this invention is as follows (all parts being by weight):

Butadiene-acrylonitrile copolymer (discrete particles) 40. Ethylene propylene copolymer l0. Polypropylene (atactic) 1S. Polyethylene ll. Paraffin wax l0. Paraffinic hydrocarbons (liquid) 13. Iron oxide 1 The ethylene propylene copolymer used in this invention is a rubbery material generally known as EPR or ethylene propylene rubber. The preferred material has an average molecular weight of about 260,000, contains about mol per cent polypropylene, has a Mooney viscosity (ASTM D1646) of about 40 and a specific gravity of about 0.86. Other olefinic elastomers chlorosulfonated polyethylene, EPDM, or combinations of these with ethylene propylene copolymers are also suitable provided that such materials have a molecular weight within the range from about 50,000 to about 900,000. When ethylene-propylene rubber is used, the propylene content can range from about 30-90 mol percent.

The butadiene-acrylonitrile copolymer used in this composition is a finely divided powder up to about 1 "mm. in'diameter which is insoluble inthe remainder of the composition and is generally known as high acrylonitrile polymer. It has a molecular weight range of 300,000 to 1,000,000 and particularly about 500,000, an acrylonitrile content of about 40 percent, has a Mooney viscosity (ASTM D1646) of about 100-130 and a specific gravity of about 1.0. Other butadieneacrylonitrile copolymers of very high acrylonitrile content or of medium acrylonitrile content may also be used as well as butadiene-acrylonitrile polyvinyl chloride blends, butadiene-styrene copolymers and iso- -p'rene-styrene copolymers or combinations of these provided that such materials have a molecular weight propylene alloys, and other olefin polymers such as polyisobutylene' and poly 4-methyl pentene is also suitable if the physical properties and molecular weight are within the above ranges.

Polyethylenes having a meltindex within the range from about 8 to about 100, preferably from about 25, and particularly about 22 are suitable for use with this inventiomAlso' suitable are copolymers of I ethylene such as ethylene vinyl acetate, ethylene ethyl acrylate, and ethylene methylrnethacrylate. Also suitable are crosslinked polyethylene'and chlorinated polyethylene, as long as the polymer is within the above melt index range. Ethylene polymers for use in this invention have a specific gravity in the range from about 0.91-0.94, particularly about 0.92, crystallinity in the range from about 50 percent to 70 percent, particularly such as butyl rubber, natural rubber, chloroprene,

about 50 percent, and contain from about 3 to about 50 methyl groups per 100 carbon atoms.

Petroleum crystalline (not microcrystalline) paraffin wax having a melting point in the range of 100F. to 200F., preferably 150 to 170F., a specific gravity of 0.80 to 1.0, preferably about 0.95 and a penetration (ASTMD1321 mm/10 77F.) of 10 to 25, preferably 13, is suitable for use with this invention.

Paraffinic hydrocarbons suitable for use with this invention are liquids having an aniline point above about 190F., a Saybolt Universal viscosity of at least about 40 seconds and a specific gravity from about 0.86 to about 0.93, particularly about 0.89. These materials are employed primarily as plasticizers. Other suitable as propylene carbonate, dibasic acid esters such as dioctyl adipate, diisooctyl phthalate or diisodecyl adi- I the mixer jacket was replaced by steam sufficient to i plasticizers which can be used are propene esters such pate, drying oil esters such as Rohm and Haas 210H (esterified residue from sebacic acid), and polyethers such as Pluracol, a hydroxyl terminated polyether mar.- keted byWyandotte Chemicals Co., having the above physical properties. g

It is often desirable, but not essential, to employ a colorant in the blend of this composition. One example of such a colorant is iron oxide (Fe O Other pigments may of course also be used as long as they do not interfere with the properties of the blend. Also, it may under some circumstances be desirable to add inert fillers to the composition. I

The above-described components can vary as to their aproximate weight per cent in the overall composition as follows:

Broad Preferred Range Range Ethylene Propylene Rubber 525% 8-15% Butadiene-Acrylonitrile Copoly-' mer 20-50% 30-40% Atactic polypropylene 10-30% 10-15% Polyethylene i f 5-30% 10-20% High melting point paraffin wax l-20% 515% Paraffinic oil 10-30% 10-15% Colorant 0l0% 0.1-1

An example of a preferred sealant composition is set forth below.

Example This blend was mixed in a clean kneading-type semiintensive Baker-Perkins mixer jacketed for heating and cooling. (Either, a dispersion type or sigma type blade can be used.) With pipe temperature cooling water on, the ethylene propylene rubber was added to the mixer and mixed for a 'shorttime. Then while still mixing, atactic polypropylene was added, followed by polyethylene andiron oxide. The paraffin wax and paraffinic oil were then blended into the mixture. At the beginning of addition of the polyethylene, the water in achieve a mixing temperature between about 240 and 260F.

The sealant described in the'above example and the other sealants within the scope of this invention can be handled within a rangeof temperature from about to about 350F., preferably about 225-275F. and particularly about 250F. When applied to other materials at such temperatures, adherence will result. Of course, the temperature of application should not exceed a temperature which would damage any of the cable components. There is substantially no shrinkage of the sealant upon cooling. The viscosity of sealants within the scope of this invention, as measured by Brabender plastograph, is in the range from about 200 to about 300 meter-grams at 250F.

These novel compositions possess many of the characteristics normally associated with cured elastomers such as polysulfides and SBR but are capable of being deposited in a plastic state under the influence of heat and pressure into the interstices of cable.

The sealants of this invention are of unusually low specific gravity, i.e. from about 0.8 1.35, preferably 0.82 0.93 and particularly about 0.88.

Although this invention is particularly useful as a sealant for electrical cable, its use is, of course, not limited to this particular application. Many other applications will be apparent to those skilled in the plastic and sealant arts.

APPENDIX Set forth below are commercial materials which were used in the Example. Of course, numerous other materials having properties within the ranges previously specified can also be used.

1. A cable comprising a plurality of strands, voids between said strands, wherein'the voids are filled with a composition of matter comprising a normally noncuring blend of from about:

a. 5-25 percent by weight of a material selected from the group consisting of ethylene propylene rubber, butyl rubber, natural rubber, chloroprene, chlorosulfonated polyethylene, EPDM and mixtures thereof having a molecular weight within the range from about 50,000 to about 900,000,

b. 20-50 percent of a material selected from the group consisting of butadiene-acrylonitrile copolymers, butadiene-styrene copolymers, isoprenestyrene copolymers, and butadieneacrylonitrilepolyvinyl chloride blends, the material selected having a specific gravity of about 1, a Mooney viscosity of about 100 to 130 and a molecular weight of about 300,000 to 1,000,000,

c. -30 percent of a material selected from the group consisting of atactic polypropylene and blends of atactic polypropylene with, polychloroprene, SBR, EPDM, polyisobutylene and poly 4- methyl pentene the material selected having a specific gravity of about 0.87 to 0.93, a melt point of about 100 250C and an average molecular weight of about 10,000 to 600,000,

d. 5-30 percent of a material selected from the group consisting of polyethylene, ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, ethylene-methyl methacrylate copolymers, crosslinked polyethylene and chlorinated poly-ethylene, the material selected having a melt index within the range from about 8 to about 100, a density of about 0.91 0.94, a crystallinity of about 50 percent and containing 3-50 methyl groups per carbon atoms,

e. 1-20 percent of petroleum crystalline paraffin wax having a melting point in the range of 100F to 200F, a specific gravity of 0.80 1.0 and a penetration of 10 to 25 mm per 10 seconds and f. 10-3O percent of a material selected from the group consisting of liquid paraffinic hydrocarbons having an aniline point above 190F, a Saybolt Universal viscosity of at least about 40 seconds and a specific gravity from about 0.86 to about 0.93, propylene carbonate, dioctyl adipate, diisooctyl phthalate, diisodecyl adipate and hydroxyl terminated polyethers.

2. A cable comprising at least one strand, a cover surrounding said strand, and void space between said strand and said cover, wherein said void space is filled with a composition of matter comprising a normally non-curing blend of from about:

a. 5-25 percent by weight of a material selected from the group consisting of ethylene propylene rubber, butyl rubber, natural rubber, chloroprene, chlorosulfonated polyethylene, EPDM and mixtures therof having a molecular weight within the range from about 50,000 to about 900,000,

b. 20-50 percent of a material selected from the group consisting of butadiene-acrylonitrile copolymers, butadiene-styrene copolymers, isoprenestyrene copolymers, and butadiene-acrylonitrilepolyvinyl chloride blends, the material selected having a specific gravity of about 1, a Mooney viscosity of about 100 to and a molecular weight of about 300,000 to 1,000,000,

c. 10-30 percent of a material selected from the group consisting of atactic polypropylene and blends of atactic polypropylene with propylene alloys, polychloroprene, SBR, EPDM, polyisobutylene and poly 4-methyl pentene the material selected having a specific gravity of about 0.87 to 0.93, a melt point of about 100 250C and an average molecular weight of about 10,000 to 600,000,

d 5-30 percent of a material selected from the group consisting of polyethylene, ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, ethylene-methyl methacrylate copolymers, crosslinked polyethylene and chlorinated polyethylene, the material selected having a melt index within the range from about 8 to about 100, a density of about 0.91 0.94, a crystallinity of about 50 70 percent and containing 3-50 methyl groups per 100 carbon atoms,

e. l-20 percent of petroleum crystalline paraffin wax having a melting point in the range of 100F to 200F, a specific gravity of 0.80 1.0 and a penetration of 10 to 25 mm per 10 seconds, and

I f. 10-30 percent of a material selected from the group consisting of liquid paraffinic hydrocarbons having an'aniline point above 190F, a Saybolt Universal viscosity of at least about 40 seconds and a specific gravityfromabout 0.86 to about 0.93, propylene carbonate, dioctyl adipate, diisooctyl phthalate, diisodecyl adipate and hydroxyl terminated polyethers,

3. A method of sealing voids between the strands of b. -50 percent'of a material selected from the group consisting of butadiene-acrylonitrile copolymers, butadienestyrene copolymers, isoprenestyrene copolymers, and butadieneacrylonitrile polyvinyl chloride blends, the material selected having a specific gravity of about l, a Mooney viscosity of about 1.00 to 130 and a molecular weight of about 300,000 to l,000,000

c. l030 percent of a material selected from the group consisting of atactic polypropylene and blends of atactic polypropylene with polychloro- 8 prene, SBR, EPDM, polyisobutylene and poly 4- methyl pentene, the material selected having a spe- I cific gravity of about 0.87 to 0.93, a melt point of about 100 250C and an average molecular weight of about 10,000 to 600,000,

d. 5 30 percent of a material selected from the group consisting of polyethylene, ethylene-vinyl acetate copolymers, ethyleneethyl acrylate copolymers, ethylene-methyl methacrylate copolymers, crosslinked polyethylene and chlorinated polyethylene, the material selected having a melt index within the range from about 8 to about 100, a density of about 0.91 0.94, a crystallinity of about 50 percent and containing 3-50 methyl groups per carbon atoms,

e. l-20 percent of petroleum crystalline paraffin wax having a melting point in the range of l00F to 200F, a specific gravity of 0.80 1.0 and a penetration of 10 to 25 mm per 10 seconds, and

f. l0-30 percent of a material selected from the group consisting of liquid paraffinic hydrocarbons having an aniline point above F, a Saybolt Universal viscosity of at least about 40 seconds and a specific gravity from about 0.86 to about 0.93,

propylene carbonate, dioctyl adipate, diisooctyl.

phthalate, diisodecyl adipate and hydroxyl terminated polyethers.

4. The method of claim wherein the temperature employed is between about 225 and 275F. 

2. A cable comprising at least one strand, a cover surrounding said strand, and void space between said strand and said cover, wherein said void space is filled with a composition of matter comprising a normally non-curing blend of from about: a. 5-25 percent by weight of a material selected from the group consisting of ethylene propylene rubber, butyl rubber, natural rubber, chloroprene, chlorosulfonated polyethylene, EPDM and mixtures therof having a molecular weight within the range from about 50,000 to about 900,000, b. 20-50 percent of a material selected from the group consisting of butadiene-acrylonitrile copolymers, butadiene-styrene copolymers, isoprene-styrene copolymers, and butadiene-acrylonitrile-polyvinyl chloride blends, the material selected having a spEcific gravity of about 1, a Mooney viscosity of about 100 to 130 and a molecular weight of about 300,000 to 1, 000,000, c. 10-30 percent of a material selected from the group consisting of atactic polypropylene and blends of atactic polypropylene with propylene alloys, polychloroprene, SBR, EPDM, polyisobutylene and poly 4-methyl pentene the material selected having a specific gravity of about 0.87 to 0.93, a melt point of about 100* - 250*C and an average molecular weight of about 10,000 to 600,000, d 5-30 percent of a material selected from the group consisting of polyethylene, ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, ethylene-methyl methacrylate copolymers, cross-linked polyethylene and chlorinated polyethylene, the material selected having a melt index within the range from about 8 to about 100, a density of about 0.91 -0.94, a crystallinity of about 50 - 70 percent and containing 3-50 methyl groups per 100 carbon atoms, e. 1-20 percent of petroleum crystalline paraffin wax having a melting point in the range of 100*F to 200*F, a specific gravity of 0.80 - 1.0 and a penetration of 10 to 25 mm per 10 seconds, and f. 10-30 percent of a material selected from the group consisting of liquid paraffinic hydrocarbons having an aniline point above 190*F, a Saybolt Universal viscosity of at least about 40 seconds and a specific gravity from about 0.86 to about 0.93, propylene carbonate, dioctyl adipate, diisooctyl phthalate, diisodecyl adipate and hydroxyl terminated polyethers.
 3. A method of sealing voids between the strands of cable comprising filling said voids, at a temperature above about 170*F. and below a temperature which would damage the cable components, with a composition of matter comprising a normally non-curing blend of from about: a. 5-25 percent by weight of a material selected from the group consisting of ethylene propylene rubber, butyl rubber, natural rubber, chloroprene, chlorosulfonated polyethylene, EPDM and mixtures thereof having a molecular weight within the range from about 50,000 to about 900,000, b. 20-50 percent of a material selected from the group consisting of butadiene-acrylonitrile copolymers, butadiene-styrene copolymers, isoprene-styrene copolymers, and butadieneacrylonitrile polyvinyl chloride blends, the material selected having a specific gravity of about 1, a Mooney viscosity of about 100 to 130 and a molecular weight of about 300,000 to 1,000,000 c. 10-30 percent of a material selected from the group consisting of atactic polypropylene and blends of atactic polypropylene with polychloroprene, SBR, EPDM, polyisobutylene and poly 4-methyl pentene, the material selected having a specific gravity of about 0.87 to 0.93, a melt point of about 100*- 250*C and an average molecular weight of about 10,000 to 600,000, d. 5-30 percent of a material selected from the group consisting of polyethylene, ethylene-vinyl acetate copolymers, ethyleneethyl acrylate copolymers, ethylene-methyl methacrylate copolymers, cross-linked polyethylene and chlorinated polyethylene, the material selected having a melt index within the range from about 8 to about 100, a density of about 0.91 -0.94, a crystallinity of about 50 - 70 percent and containing 3-50 methyl groups per 100 carbon atoms, e. 1-20 percent of petroleum crystalline paraffin wax having a melting point in the range of 100*F to 200*F, a specific gravity of 0.80 - 1.0 and a penetration of 10 to 25 mm per 10 seconds, and f. 10-30 percent of a material selected from the group consisting of liquid paraffinic hydrocarbons having an aniline point above 190*F, a Saybolt Universal viscosity of at least about 40 seconds and a specific gravity from about 0.86 to about 0.93, propylene carbonate, dioctyl adipate, diisooctyl phthalate, diisodecyl adipate and hydroxyl terminated polyethers.
 4. The method of claim 3 wherein the temperature employed is between about 225* and 275*F. 